Deep brain stimulation (DBS) is a surgical procedure involving the implantation of a medical device called a macroelectrode (also referred to as a “lead”, “brain pacemaker”, “electrode” or “chronic electrode”), which sends electrical impulses to specific parts of the brain. DBS in select brain regions has provided noticeable therapeutic benefits for otherwise treatment-resistant movement and affective disorders such as chronic pain, Parkinson's disease, tremor, dystonia and depression. At present, the procedure is used only for patients whose symptoms cannot be adequately controlled with medications. DBS directly changes brain activity in a controlled manner, and its effects are reversible (unlike those of lesioning techniques).
DBS uses the surgically implanted, battery-operated medical neurostimulator to deliver electrical stimulation to targeted areas in the brain that control movement, blocking the abnormal nerve signals that cause tremor and PD symptoms.
Before the procedure, a neurosurgeon uses magnetic resonance imaging (MRI) or computed tomography (CT) scanning to identify and locate the exact target within the brain. For treating movement disorders, these targets are areas that control movement, such as the thalamus, subthalamic nucleus, and globus pallidus where electrical nerve signals generate the undesired symptoms.
The DBS system consists of three components: the macroelectrode, the extension, and the neurostimulator. The macroelectrode—a thin, insulated wire—is inserted through a small opening in the skull and implanted in the brain. The tip of the electrode is positioned within the targeted brain area.
The extension is an insulated wire that is passed under the skin of the head, neck, and shoulder, connecting the lead to the neurostimulator. The neurostimulator (the “battery pack”) is the third component and is usually implanted under the skin near the collarbone. In some cases it may be implanted lower in the chest or under the skin over the abdomen.
Once the system is in place, electrical impulses are sent from the neurostimulator up along the extension wire and the lead and into the brain. These impulses interfere with and block the electrical signals that cause the undesired symptoms. The person has the possibility turn the DBS off if required.
Accurate placement of the macroelectrode is critical in order to improve the effectiveness of the installed macroelectrode. There is thus a need in the field to map in the most precise manner available, the target region for inserting a macroelectrode.